Fuel injection nozzles

ABSTRACT

A liquid fuel injection nozzle unit for an internal combustion engine includes a valve member movable towards a seating to prevent fuel flow through an outlet from an inlet the valve member is engaged by a push rod which is subjected to the fluid pressure in the inlet by way of a non-return valve, the area of the push rod exposed to the fluid pressure being less than that of the valve member which is exposed to the fluid pressure whereby the valve member will be lifted from its seating to allow flow through said outlet.

United States Patent [191 Fenne Au 27 1974 [54] FUEL INJECTION NOZZLES 3,747,857 7/1973 Fenne 239/533 x [75] Inventor: Ivor Fenne, Middlesex, England P Ex M H wood J I rzmary ammerenson r. Asslgneei Llmlteds Blmllngham, Assistant Examiner-Michael Y. Mar

England Attorney, Agent, or Firm-Holman & Stern [22] Filed: Jan. 15, 1973 21 Appl. No.: 323,529 [57] ABSTRACT A liquid fuel injection nozzle unit for an internal com- [30] Foreign Application Priority Data bustion engine includes a valve member movable Jan 1 5 1972 Great Britain 20] 8/72 towards a seating to prevent fuel flow through an outlet from an inlet the valve member is engaged by a push rod which is subjected to the fluid pressure in the 5%] (5|. inlet by way of a nomremm valve, the area of the d 33 9O 9 6 push rod exposed to the fluid pressure being less than 1 o are that of the valve member which is exposed to the fluid pressure whereby the valve member will be lifted from [56] u lTE g s qg g gs gg r Ts its seating to allow flow through said outlet. 3738,576 6/1973 ONeill 239/533 2 Claims, 1 Drawing Figure iii fl FUEL INJECTION NOZZLES This invention relates to fuel injection nozzles for use with compression ignition engines, the nozzles being of the kind comprising a nozzle body having a nozzle head at one end thereof, a valve member slidable within the head and movable under the action of fuel under pressure away from a seating to allow flow of fuel from an inlet through an outlet, and a spring for effecting movement of the valve member into contact with the seating.

The object of the invention is to provide such a nozzle in a simple and convenient form.

According to the invention in a nozzle of the kind specified the valve member or an elongated member acting intermediate the valve member and the spring,

is divided to define a space to which fuel under pres- An example of a fuel injection nozzle in accordance I with the invention will now be described with reference to the accompanying drawing which shows a sectional side elevation of the nozzle. Referring to the drawing, there is provided a nozzle body which at one end mounts a nozzel head 11, the head being retained relative to the body by means of a retaining member 12 which is in screw-thread engagement with the body.

Formed in the nozzlehead 11 is a bore 13 in which is slidably mounted a valve member 14. The end of the bore defines a seating for the valve .member 14 and when the valve member is moved away from the seating, fuel can flow from the bore through an outlet 15 into a combustion space of an associated engine. The bore is enlarged to provide an annular chamber 16 and this communicates by way of a passage 17 continuing through the body 10, with an inlet 18. The inlet is connected to a pump 19 which is' driven in timed relationship with the associated engine.

Extending within the body 10 is a drilling 20 having a diameter smaller than that of the bore 13 and located within the drilling is a divided elongated push member 21a, 21b. The end of the portion 21a of the push member is of reduced diameter and the adjacent end of the other portion of the push member is of spherical form. There is thus defined with the wall of the drilling 20 an annular space 22 to which fuel under pressure may be supplied from the inlet 18 by way of a spring-loaded non-return valve 23.

The upper portion 21a of the push member mounts an abutment 24 for a coiled compression spring 25. The compression spring is located within a cap member 26 which is in screw-thread engagement with the body. Extending within the spring is a stop member 27 which can co-operate with the spring abutment 24 to limit the extent by which the spring can be compressed. The chamber containing the spring communicates with either the atmosphere or a source of fuel at a low pressure by way of a drilling formed in the stop member 27, and also communicating with the space containing the spring is the end of the bore 13 remote from the outlet 15.

In operation, when the pump is at rest the two portions of the push member will be in abutment with each other and the valve member 14 will be retained upon its seating by the action of the spring 25. When fuel is supplied to the inlet as for instance when the engine is being started fuel under pressure will be supplied to the aforesaid space 22 but the force acting to separate the two portions of the push member created by this pressure, will be insufficient to overcome the force exerted by thespring. As a result, the nozzle will operate in the conventional manner and the valve member will be returned to its seating when the flow of fuel ceases, by the action of the spring 25.

As the pressure of fuel delivered by the pump 19 increases a point will be reached at which the force developed by the pressure of fuel within the space 22 is sufficient to separate the two portions of the push member so that the spring abutment 24 is moved into contact with the stop 27. When this occurs the spring plays no further part in the operation of the nozzle and the movement of the valve member 14 onto its seating at the end of the injection period is achieved by the pressure of fuel within the space 22. It will be appreciated that the pressure of fuel applied to the valve member 14 to lift it from its seating will be substantially equal to the pressure of fuel within the aforesaid space. However, the area of the lower portion 21b of the push rod which is exposed to the pressure in the space is sub stantially smallerthan the area of the valve member which is exposed to the same pressure. As a resultof this when fuel under pressure is supplied to the inlet 18 the valve member 14 will move in the direction away from its seating to permit flow of fuel through the outlet 15. i

The volume of the space 22 must be sufficient to prevent an excessive rise in pressure when the portion 21b of the push member is moved by the action of valve member 14 and small enough to allow the pressure in space 22 to drop owing to leakage when the engine speed is lowered. The action of the one way valve 23 is to trap fuel in the space 22 at the peak pressure occuring during the delivery of fuel by the pump.

The nozzle described possesses the important feature that the nozzle opening pressure is a function of the peak inlet pressure as also is the closing pressure when the abutment is in contact with the stop, and this has the effect of increasing the effective rate of injection of fuel at high speeds.

Furthermore, once the spring has ceased to operate then the moving mass of the construction is less than that of a conventional injector.

By careful choice of the spring load and the diameter of the push member the pressure at which the effect of the spring becomes zero can be predetermined.

In the particular example, it is to be noted that a push member is interposed between the valve member and the spring. However, in some instances the push member is dispensed with and the valve member is made of increased length. In this instance the valve member itself would be divided to define the aforementioned space, it being appreicated that it would be necessary to provide a step on the valve member to produce the differential force required to effect opening of the valve member.

.I claim:

l. A fuel injection nozzle for use with compression ignition engines, the nozzle comprising a nozzle body having a nozzle head at one end thereof, an inlet in the body, a valve member slidable within the head; a seating defined in the head, a spring for effecting movement of the valve member onto the seating, the valve member being lifted from the seating by fuel under pressure supplied to the inlet and acting on the end of the valve member adjacent the seating, connection means disposed intermediate the valve member and spring, said connection means being divided to define a space, passage means through which fuel under pressure can be supplied from said inlet to said space, a non-return valve disposed in said passage means, the arrangement being such that when the pressure of fuel supplied to the inlet is low the nozzle operates in the conventional manner with the spring being operative to close the valve member onto the seating but as the pressure of fuel increases a point is reached at which the pressure within the space compresses the spring its maximum extent whereafter the valve member is closed onto the seating by the action of the pressure of fuel within the space, the area of the connection means subjected to the pressure of fuel at the inlet being less than area of the valve member subjected to said pressure.

2. A nozzle as claimed in claim 1 including means limiting the deflection of said spring. 

1. A fuel injection nozzle for use with compression ignition engines, the nozzle comprising a nozzle body having a nozzle head at one end thereof, an inlet in the body, a valve member slidable within the head; a seating defined in the head, a spring for effecting movement of the valve member onto the seating, the vAlve member being lifted from the seating by fuel under pressure supplied to the inlet and acting on the end of the valve member adjacent the seating, connection means disposed intermediate the valve member and spring, said connection means being divided to define a space, passage means through which fuel under pressure can be supplied from said inlet to said space, a non-return valve disposed in said passage means, the arrangement being such that when the pressure of fuel supplied to the inlet is low the nozzle operates in the conventional manner with the spring being operative to close the valve member onto the seating but as the pressure of fuel increases a point is reached at which the pressure within the space compresses the spring its maximum extent whereafter the valve member is closed onto the seating by the action of the pressure of fuel within the space, the area of the connection means subjected to the pressure of fuel at the inlet being less than area of the valve member subjected to said pressure.
 2. A nozzle as claimed in claim 1 including means limiting the deflection of said spring. 